Sleep Calculator

Total sleep and full 90-minute cycles, from bedtime to wake time.

FREE TOOL · WORKS OFFLINE · NO SIGN-UP

Results update instantly as you type.

Total sleep
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Total minutes
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Full 90-minute cycles
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Cycle sleep time
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How to Use This Sleep Calculator

  1. 1.Set your bedtime. When you actually fall asleep, not just when you get into bed.
  2. 2.Set your wake time. When your alarm goes off or you naturally wake up.
  3. 3.Read the total. The calculator handles overnight sleep that crosses midnight for you.
  4. 4.Count the cycles. Sleep runs in roughly 90-minute cycles; waking at the end of one usually feels easier.
  5. 5.Aim for whole cycles. Five cycles is 7 hours 30 minutes; six cycles is 9 hours.

FAQ

How much sleep is 11:00 PM to 7:00 AM?

11:00 PM to 7:00 AM is 8 hours of sleep, which holds 5 full 90-minute cycles. Five cycles take 7 hours 30 minutes, leaving 30 minutes of partial-cycle sleep.

What is a 90-minute sleep cycle?

Sleep moves through light sleep, deep sleep and REM in a cycle of roughly 90 minutes. Waking up at the end of a cycle, rather than in the middle of deep sleep, usually feels less groggy.

How many cycles should I aim for?

Most adults do well on 5 cycles (7 hours 30 minutes) or 6 cycles (9 hours). Fewer than 4 cycles, which is 6 hours, leaves most people short on sleep over time.

Is this sleep calculator free?

Yes — 100% free, no sign-up, no limits. Everything runs in your browser; none of your numbers are uploaded or saved.

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